The conversion of energy regularly results in energy being lost in the form of heat. This applies to both the conversion of thee kinetic energy of wind into electrical energy in the generator of a wind energy facility, where these losses regularly occur in the main driving line of the wind energy facility, and also for the electrical feeding of energy generated by the wind energy facility into a medium voltage network. For this purpose, regular devices of power electronics, e.g., rectifiers, and/or transformers, are necessary. In the main driving line, which is mounted in the nacelle for a wind energy facility, the losses occur overwhelmingly in the gears, at the bearings, and in the generator or at other control units, such as, e.g., in the hydraulic systems or similar control and regulation units, which adjust the rotor blades or turn the wind energy facility into the wind. For gearless wind energy facilities, e.g., model E-66 of Enercon, the main losses occur at the main driving line in the generator, i.e., in the nacelle (head) of the wind energy facility.
For the power supply, losses occur overwhelmingly at the power transformer and, if necessary, in the power electronics, e.g., in the rectifier.
For a 1.5 MW wind energy facility, the losses can be in the range of 60-100 kW. Up until now, these losses ere dissipated into the environment by means of fans. In this way, cold air is suctioned in from the outside by the fans to cool the corresponding components, e.g., the generator. The heated air is then blown back outside.
Consideration has also already been given to cooling the generator with water and to then cooling the heated water back down with a heat exchanger. All of these known solutions have in common a large amount of air that is always needed from the outside. This is particularly disadvantageous if the outside air is humid or, particularly in coastal regions, if it has a high salt content, and the cooling elements are then exposed to this humid and high salt content air. This problem is especially extreme with wind energy facilities that stand directly on the coast or, in offshore technology, directly in salt water.
One object of the invention is to provide a cooling device for a wind energy facility which reduces its losses.
The basic concept of the invention is to provide a completely closed or in an alternative embodiment, a partially closed cooling circuit for a wind energy facility, so that no or practically no outside air has to be used for cooling. In this way, the cooling air circulates within the wind energy facility from its nacelle to the tower or to the base of the wind energy facility and the energy stored by the coolant, preferably air, during the cooling is dissipated by means of the tower of the wind energy facility. The tower of the wind energy facility is always exposed to the wind, so that the tower of the wind energy facility acts as a cooling element or a heat exchanger, which dissipates the stored energy to the wind enveloping the tower.
Another advantage of the concept according to the invention is that the tower is also heated from the inside out for very cold outside temperatures of approximately xe2x88x9220xc2x0 to xe2x88x9230xc2x0 C. by its function as a heat exchanger and a load-bearing part of the wind energy facility. Due to this fact, the wind energy facility can remain in operation. According to the state of the art up until now, a special cold-resistant steel had to be used for very cold locations, such as, e.g., northern Sweden, Norway, Finland, Canada, etc.
If desired, due to very low outside temperatures below the freezing point, it is also possible to combine the heating of the rotor blades with the cooling circuit, so that the rotor blades can be heated with the fluid in the cooling circuit.
The coolant is cooled by the tower due to the fact that at least one air channel is formed in the tower itself (inside or outside), and the heated air flows through this channel such that the air can dissipate its energy at least partially at the tower walls.
One air channel is preferably formed such that the tower is configured with double walls, so that one part of the cooling channel is formed through the load-bearing wall of the tower.
By using the tower or rotor blades of the wind energy facility, which are usually manufactured out of steel, as a cooling element or a heat exchanger, a component that is already present and required by every wind energy facility is used for an advantageous function. Heated air flows from the generator or transformer into the steel tower at its outer wall. This outer wall has a very large surface area, e.g., for a 1.5 MW facility, approximately 500 m2, and thus offers a very large heating/cooling surface. The wind enveloping the tower continuously cools this surface.
When the blades are used a the heat exchanger, this provides rapid cooling since they present a large surface area that rotates through the wind at high speeds. The further advantage is that the rotor blades are heated, which is an advantage in ice forming conditions since it will keep the blades free of snow and ice and save the expense of providing a separate heater for the rotor blades.